1. Field of the Invention
The present invention relates to a thermoplastic resin composition having excellent impact resistance, heat resistance, chemical resistance, moldability, dimensional stability and appearance of molded articles made therefrom. This composition of the present case can be widely utilized as materials for industrial parts, electrical and electronic machine parts, automobile parts and the like.
2. Description of the Prior Art
Aromatic polyesters, polyphenylene ethers, polycarbonates, polyarylene sulfides are called the so-called engineering plastics. These compounds are believed to have mechanical properties, heat resistance, chemical resistance and the like, and they are used in many fields. In recent years, with regard to the engineering plastics, new additional functions are demanded, and various attempts have been made. One of them is a composition comprising a combination of plural engineering plastics, and this composition has features of the respective plastics and is known as a polymer alloy.
Known examples of such a polymer alloy include (1) an aromatic polyester and a polyphenylene ether, (2) an aromatic polyester, and a polycarbonate, and (3) an aromatic polyester and a polyarylene sulfide.
(1) The aromatic polyester is excellent in moldability and chemical resistance but is poor in dimensional stability and impact strength, particularly notched impact strength inconveniently. For the purpose of solving the problem, a method has been suggested in which a polyphenylene ether is mixed with the aromatic polyester. According to a different standpoint, this mixture also intends to improve moldability and solvent resistance which are drawbacks of the polyphenylene ether. However, these two resins are difficult to disperse into each other, and thus some methods for facilitating the dispersion are disclosed. In Japanese Patent Publication No. 51-21664, Japanese Patent Unexamined Publication No. 48-56742 (U.S. Pat. No. 4,013,613), particularly Japanese Patent Unexamined Publication No. 62-121760 and Japanese Patent Unexamined Publication No. 62-129345, there are described examples using ethylene copolymers modified with epoxy group-containing ethylene copolymers and epoxy group-containing compounds.
However, in the ethyelene copolymer having the epoxy group, the affinity for the aromatic polyester is good but the affinity for the polyphenylene ether is poor, and for this reason, the improvement of the impact resistance is not sufficient.
(2) When the polycarbonate is mixed with the aromatic polyester, the impact strength of the aromatic polyester can be improved, and the solvent resistance and moldability of the polycarbonate can be effectively improved. Examples in which these two resins are mixed with each other are disclosed in U.S. Pat. No. 4,172,859 (Japanese Patent Unexamined Publication No. 51-144452), EP-180648 (Japanese Patent Unexamined Publication No. 60-231757), Japanese Patent Unexamined Publication No. 61-238847, Japanese Patent Unexamined Publication No. 61-252268, Japanese Patent Unexamined Publication No. 61-235456. In these examples, copolymers of glycidyl esters and .alpha.-olefins and polyfunctional glycidyl ester compounds are used to obtain compositions excellent in impact resistance, heat resistance, appearance of molded articles made therefrom, and dry heat stability.
However, in the copolymers of glycidyl esters and .alpha.-olefins and the polyfunctional glycidyl ester compounds, the affinity for the polycarbonates is insufficient, and therefore compositions having excellent impact resistance and appearance of the molded articles cannot be obtained.
(3) A mixture of the aromatic polyester and the polyaryl sulfide can improve the heat resistance and creep resistance of the aromatic polyester and the moldability of the polyarylene sulfide. Examples of this resin mixture are disclosed in Japanese Patent Unexamined Publication Nos. 62-218441, 62-218442 and 62-218436. In all of these publications, copolymers of glycidyl esters and o-olefins are used to obtain compositions having excellent impact resistance, mechanical properties at high temperatures, hydrolysis resistance and appearance of molded articles. However, in the copolymers of gylcidy esters and .alpha.-olefins, the affinity for the polyarylene sulfide is poor, and therefore any compositions which are excellent in impact resistance and appearance of molded articles cannot be obtained.